Refrigerant evaporator



Mardi l1, 1941. c. STEL-:NSTRUP REFRIGERANT EVAPORATOR Original Filed Dec. l, 1957 Inventor" Christian Steenstru by )Va/V75 20ML/M1 His Attorney- Patented Mar. 11, 1.941

' 'UNITEDv s'rA'rEs PATENT oFFlCE c t 2,234,713 nEFnIGEaAN'r Eva1 oltafronA 'christian steentmp, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Original application December 1, 1927, Serial No. 177,495. [Divided Intl this application July 21,

1939, Serial N0. 285,702

comms. (cica-12s)- My invention relates to refrigerant evaporators compartment at relatively high temperatures so that the temperature differential between the cabinet air and the evaporator-is small and temperatures near the freezing lpoint of water may be maintained by an evaporator operatingat a temperature above freeng.l Evaporators of this type are Auseful for maintaining vthe air in refrigerated compartments at hgh relative humidity since the removal of moisture from the air by the continual formation of frosty on the evaporator surface is avoided.

Accordingly, it is an object of my invention to provide a refrigerant evaporator of the flooded type having a large surface area relative to the area in direct contact with refrigerant and an improved arrangement for circulating refrigerant therein.

Another object of my invention is to provide a refrigerant evaporator having an improved arrangement for circulating refrigerant and which is inexpensive to manufacture and may readily be constructed of sheet metal.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specication.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is a front elevation of the upper portion of a household refrigerating machine having an evaporator embodying my lnvention; Fig. 2 is an enlarged perspective view of the evaporator shown in Fig, 1; Fig. 3 is a sectional view on the line 3-3 of Fig. 2; and Fig. 4 is a view of the evaporator sheets in the at prior to bending to fo-rm the side walls of the evaporator.

Referring now to the drawing, in Fig. 1 I have shown a refrigerating machine including a cabinet IIl having a food compartment Il normally closed by a door (not shown) and a cooling unit I2 arranged within the compartment Il. A condensing unit comprising a closed casing I3, within which is larranged a motor and a compressor, and a condenser M having a refrigerant conduit I5 maintained on a removable top I6 of the cabinet IIl. During the operation of the refrigerating machine, gaseous refrigerant is compressed by the compressor with-in the casing I3 and discharged into the conduit I5 where it is cooled and liquefied by the natural circulation of air over the.

conduit. `The liquid refrigerant flowing through a connection I'I into a liquid receiver or float valve chamber I8. When a predetermined quantity of liquid refrigerant has collected in the chamber I8, a oat therein rises and the liquid refrigerant The refrigerating machine is"-provided trol mechanism 2| in response to the temperature of the cooling unit as determined by the thermostatic element 22'. The refrigerating machine thereby maintains the surface of the cooling unit I2 within a predetermined range of temperatures. The temperature range may be selected to maintain the evaporator surface always above freezing or it may be selected so that the temperature 'rises above freezing-during each cycle and thus prevents the formation of any substantial quantity of frost, the latter method of operation Abeing known as the defrosting cycle.

Referring now to Figs. 2 and 3, the coolingunit I2 comprises a housing formed of inner and outer complementary metal sheets 23 and 24 respectively, welded together face to faceand formed to provide three vertical wallsl forming the sides and back wall of the cooling. unit. Flanges 25, 26 and 21 at the tops of the walls are provided to support Athe unit within the refrigerator cabinet in such manner as to hold the top of the unit against the underside of the top wall of the compartment I I. The bottom side of the cooling unit is closed by a wall or partition 28 and ,a partition comprising two walls 29 and 30 -spaced apart to provide a dead air space may be provided to separate the housing into a plurality of compartments. lAs shown in Fig. 1', doors 3l and 32 have been provided to close the top and bottom compartments respectively. It is, therefore, not necessary to open the entire cooling chamber in order to gain access to a part thereof,

. -10 ows through a conduit or inlet connection I9 to A In order to circulate refrigerant through the side walls of the housing, I provide headers 33, 34 and 35 formed by complementary indentations in the inner and outer sheets 23 and 24 near the tops of the vertical walls of the evaporator. The headers33, 34 and 35 during normal operation of the refrigerating machine are maintained about half filled with liquid refrigerant to maintain the evaporator passages flooded and are connected above the normal liquid level by passages 36 and below the normal liquid level by passages 31 to equalize the pressures' andA liquid levels of the several headers. In order to circulate liquid refrigerant in the walls of the evaporator, I provide a plurality of passages communicating withl The arrangementof the' the several headers. circulating passages is clearly shown in Fig. 4

which represents the sheets 23 and 24 in the flatl before they are bent to form the walls of the evaporator. The headers 33, 34 and- 35 andV also the passages 36and `3 are formed by indentations in bothsheets. A plurality of .verticalor upright passages 38 and'39 are formed in the outer sheet 24, each of the headers'having a passage 38 communicating with the left'V end thereof, as shown in Fig.l 4, and a passage 39 With- Each of the-headers is the right end thereof. thereby provided -with a pair of depending passages. 'I'hese pairs of passages are connected byy a plurality of transverse passages`40 formed in the inner sheet 33. AllA ofthe passages40 are parallel to each otherv but diverge slightly from the center line of the headers 33, 34 and 35 sol that the ends of the passages 40 communicating with the vertical passages 38 are higher than the ends of the passages 40 communicating'with thevertical passages 39. The total area of the refrigerant passages may comprise aA relativelyl small portion of the area of the evaporator surface, as illustrated.

In order to supply liquid refrigerant to the passages of the evaporator, I provide a manifold 4I arranged in the sheet 24 parallel to the passages 40. One-end of the manifold is connected tothe liquid line I9 to receive liquid refrigerant, and injector ducts 42 are provided to conduct the refrigerant from the manifold into the lower ends of the passages 38. 'I'he liquid refrigerant passes through the ducts 42 and is directed upwardly into the passages 38. Since the passages 40 slant upwardly toward the passages 38 in each wall of the evaporator, there is a tendency for liquid refrigerant vaporized in the passages 40 to now into the passages 38 and thereby produce some natural circulation of liquid refrigerant toward the passages 38 and into the headers. The natural oirculation is eiective when refrigerant is not being supplied to the evaporatonand positive circula` tion in the same direction is produced by the injector action of the ducts 42 when refrigerant is being supplied to the evaporator. The positive action of the injector ducts produces a rapid circulation of refrigerant through the passages 40.

ner around their edges and between theindentations and are then bent to forni the three-sided housing as shown. It will be evident that since the passages 49 below the several headers are arranged in alignment and on the opposite side of the structure from the upright passages 38 and 39, the sheets 23 and 24 may be secured together by line welds formed along the sides of the passages 49 by a welding wheel which may traverse three Walls of the evaporator without being lifted from the sheet 23. Furthermore, the inner sheet 23 hasno vertical indentations which would inlterfere with the partition walls 29 and 30 and would require that the partitions be cut to conformto irregularities in the wall 23. Furthermore, a plurality of straight fins 43 may be secured on thev outer Wall 24 of the evaporator as shown in Fig.'2,'without interference requiring cuts or notches to make them conform to the refrigerant passages.

If it is desired to provide capacity for freezing f Y ice within the evaporator I2, a. second evaporator or freezing shelf may be'arranged withinl the housing as described and claimed in my copending application, Serial No. 177,495, filed December l, 1937, of whichthis vcase is a division.l

' During the operation of the refrigerating unit described above, gaseous refrigerant is compressed and supplied to the condenser I4 where it is' cooled and liquefied; the liquid refrigerant under f control of the iioat valve is vadmitted to the manifold 4I from the liquid line I9 and ows through the'manifold and into the passages 38 through the ducts 42. Some of the liquid refrigerant is vaporized because of the reduction of pressure on passing through the valve. The injection of liquid and gaseous refrigerant 'through the ducts 42 induces a rapid circulation of refrigerant from the passages 39 to the passages 38 through the cross passages 40, refrigerant owinLg to the headers 33, 34 and 35 where the gaseous refrigerant is collected and removed through the suction line 28 and is returned to the compressor within the casing I3.

In order to obtain maximum use of the surface of the evaporator, the unit is preferably arranged within the refrigerator cabinet so that it is spaced from the side and back walls of the compartment to be cooled and so that air may circulate freely over all sides of the evaporator. The large cooling area thus provided makes it possible to operate the evaporator compartment at much higher temperatures than are necessary when a. small evaporator surface is employed. The arrangement of the passages in the walls of the cooling unit illustrated is such that liquid refrigerant may be circulated effectively and thereby facilitate the maintaining of even temperatures by operation of the automatic control even though the refrigerant is in direct contact with a relatively small area of the evaporator surface.

While I have shown a particular embodiment of my invention in connection with a household refrigerating machine, other modifications kwill readily be apparent to those skilled inthe art. I do not, therefore, desire my invention to be limited to the construction shown and described, and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

`What I claim as new and desire to secure by Letters Patent of the United States is:

l. A flooded evaporator for refrigerating machines comprising a substantially vertical wall having formed therein "a header and two upright passages communicating therewith and depending therefrom and a plurality of transverse passages connecting said upright passages for circulating refrigerant in saidwall, each of said transverse passages communicating with one of said upright passages at a higher point than with the other of said upright passages, means for supplying refrigerant to said passages and for withdrawing refrigerant from said header, said supplying means including means for injecting refrigerant upwardly into said one of said upright passages for producing a circulation of refrigerant through said transverse passages from the other of said upright passages to said one upright passage.

2. A flooded evaporator for refrigerating machines including complementary metal sheets secured together to form an upwardly extending wall, a refrigerant header formed between said sheets near the upper end thereof, a pair of substantially parallel passages extending from said header and formed in one of said sheets, means including a plurality of transverse passages formed in the other of saidl sheets for connecting said first-mentioned passages, said transverse passages being inclined upwardly from one of said parallel passages to the other of said parallel passages, an inlet connection for admitting liquid refrigerant to said passages, and an outlet connection for removing gaseous refrigerant from said header.

3. A flooded evaporator for refrigerating machines including complementary metal sheets secured together to form an upwardly extending wall, a refrigerant header formed between said sheets near the upper end thereof, a pair of substantially parallel passages extending from said header and formed in one of said sheets, a plurality of transverse passages formed in the other of said sheets for connecting said first-mentioned passages, means including an inlet connection for injecting liquid refrigerant upwardly into one of said parallel passages to produce a circulation of refrigerant through said transverse passages from the other of said parallel passages to said one parallel passage, and an outlet connection for removing gaseous refrigerant from said header. f

4. Aflooded evaporator for refrigerating machines including a substantially vertical wall comprising two complementary metal sheets, means including a header formed between said sheets with two upright passages communicating therewith and depending therefrom and a plurality of transverse passages connecting said upright passages for 'circulating refrigerant in said wall, said upright passages being formed in one of said sheets and said transverse passages in the other of said sheets, means for supplying liquid remeans injecting refrigerant upwardly into said one of said upright passages for producing a circulation of refrigerant through said transverse passages from the other of said upright passages to said one upright passage.

5. A flooded evaporator for refrigerating machines including a substantially vertical wall comprising two complementary metal sheets, means including a header formed between said sheets and two upright passages communicating Vtherewith and depending therefrom and a plurality of transverse passages connecting said upright passages for circulating refrigerant in said wall, said upright passages being formed in one of said sheets and said transverse passages in the other of said sheets, means for supplying liquid refrigerant to said passages and for withdrawing gaseous refrigerant from said header, each of said transversepassages communicating with one of said upright passages at a higher point than with the other of said upright passages, means injecting refrigerant upwardly into one of said upright passages for producing a circulation of refrigerant through said transverse passages from the other of said upright passages to said one upright passage, and means including a plurality of fins secured on said one sheet substantially parallel to said upright passages for increasing the surface of said evaporator.

6. A flooded evaporator for refrigerating machines comprising a plurality of substantially vertical walls, each of said walls having a header formed near the top thereof and two upright passages communicating therewith and depending therefrom and a plurality of transverse passages connecting said upright passages, means for supplying refrigerant to said passages and for withdrawing refrigerant from one of said headers, means providing communication between said headers, each of said transverse passages in each of said walls communicating with one-,of the upright passages in said Wall at Ia higher point than with the otherv of said upright passages in said wall, and meansinjecting refrigerant upwardly into said one of said upright passages in each cf said walls for producing a circulation of refrigerant through said transverse passages,

said refrigerant injecting means including a y 

